From Back to Front: Rails To React Family
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Transcript of From Back to Front: Rails To React Family
From Back to Front:Rails to React Family
Khor Soon Hin, @neth_6
Outline● React Family: ReactJS/Flux/RelayJS/GraphQL● What makes them interesting?● What are they? How they work together?● How do I get started easily?● Should I use them all?● IMPORTANT: How to get them onto Rails
React/Flux/Relay/GraphQL: In A Sentence Each
● React: UI● Flux: Data Flow● GraphQL: Data Retrieval● Relay: Component-Data Co-location
React/Flux/Relay/GraphQL: Common Goal
Improve software quality given the same development time
React/Flux/Relay/GraphQL: Common Goal
Improve software quality given the same development time
● Easy to understand & debug● Less prone to error
React/Flux/Relay/GraphQL: Common Approach
Simplify abstraction to push common tasks/code organization to pattern/framework
React/Flux/Relay/GraphQL: Common Approach
Simplify abstraction to push common tasks/code organization to pattern/framework
● Easy to understand & debug
React/Flux/Relay/GraphQL: Common Approach
Simplify abstraction to push common tasks/code organization to pattern/framework
● Easy to understand & debug● Less prone to error
React/Flux/Relay/GraphQL: Common Outcome
Functional/Declarative Programming
React: UI
React
● Single-Page Application (SPA)
Courtesy: https://facebook.github.io/react/docs/thinking-in-react.html
React (cont.)
● Single-Page Application (SPA)● Cascading Views
React (cont.)
● Single-Page Application (SPA)● Cascading Views
React (cont.)Abstraction
Each React element knows:
● The data it needs● How to render itself with HTML fragments● The data it passes to its children
React (cont.)
● Single-Page Application (SPA)● Cascading Views
Fetch Data
React (cont.)
● Single-Page Application (SPA)● Cascading Views
React (cont.)
● Single-Page Application (SPA)● Cascading Views
React (cont.)
● Single-Page Application (SPA)● Cascading Views
Uni-directional Flow
React (cont.)
● Single-Page Application (SPA)● Cascading Views
Debug Upwards
React (cont.)
jQuery: You need to find all the pieces of code that modified the UI in error
React: User Interaction
ball
React: User Interaction (cont.)
ball
React: Data Change (cont.)
ball
React: User Interaction (cont.)
ball
React: User Interaction (cont.)
jQuery: You need to find element to modify and make modification
Imperative vs. Functional: Coding● Imperative:
○ Example: jQuery code■ Code is likely in a monolithic Javascript■ Hold element ids for where each piece of data should be shown■ Retrieves element and display data■ Complex model requires customized code:
● Find pieces of data, and update pieces of element
● Functional:○ Example: React code
■ Code is contained within each React element:■ Each React element declares which part of data to pass on to children■ Each React element declares how to render data it receives■ Simplified model reduces code relinquish more to framework:
● Provide data to top view, and cascading views redraws themselves
Functional vs. Imperative: Benefits● Imperative:
○ Complex model requires customized code■ Dig through customized code to understand relationships■ Different pieces of code to initialize UI, and update based on interaction
● Functional:○ Simplified model reduces code relinquish more to framework
■ Relationship and data-flow is top-down■ Same piece of code to initialize, and update UI
React On Rails● https://github.com/reactjs/react-rails● app/assets/javascripts/components/xxxxx.js
○ Dump all your React components related to xxxxx
React: Codevar DATA = [ { category: 'Sporting Goods', products: [ {price: '$49.99', stocked: true, name: 'Football'}, {price: '$9.99', stocked: true, name: 'Baseball'}, {price: '$29.99', stocked: false, name: 'Basketball'}, ], }, { category: 'Electronics', products: [ {price: '$99.99', stocked: true, name: 'iPod Touch'}, {price: '$399.99', stocked: false, name: 'iPhone 5'}, {price: '$199.99', stocked: true, name: 'Nexus 7'}, ], },];
React: Code (cont.)// Javascript required in app/assets/javascripts/application.js
ReactDOM.render( <ProductTable data={DATA} />, document.getElementById('container'));
React: Code (cont.)
// app/assets/javascripts/components/product.jsx
var ProductTable = React.createClass( render: function() { var rows = []; this.props.data.forEach(function(dataElem) { rows.push(<ProductCategoryRow category={dataElem.category} … />); dataElem.products.forEach(function(product) { rows.push(<ProductRow product={product} … />); }); ...
var DATA = [ { category: 'Sporting Goods', products: [ {name: 'Football', ...}, {name: ’Baseball’, ... }, ... ], }, { category: 'Electronics', products: [ {name: 'iPod Touch', ...}, {name: ‘iPhone 6’, …}, ... ], },];
React: Code (cont.)
// app/assets/javascripts/components/product.jsx
var ProductCategoryRow = React.createClass({ render: function() { return (<tr><th>{this.props.category}</th></tr>); }});
React: Code (cont.)// app/assets/javascripts/components/product.jsx
var ProductRow = React.createClass({ render: function() {
return ( <tr> <td>{this.props.product.name}</td> <td>{this.props.product.price}</td> </tr> );
}});
React: SummarySimplify abstraction
● UI○ Shove data for entire UI from the top component○ Each component render itself with data for self○ Each component pass data to child○ To change component, just change data
Framework
● Handle initializing/updating UI with the right pieces of data
How
● Re-drawing all UI pieces efficiently
Flux: Data Flow
React
Courtesy: https://facebook.github.io/react/docs/thinking-in-react.html
MVC
Courtesy: http://fluxxor.com/what-is-flux.html
Multiple Models/Domains
Chat
News
Summary
Friend Requests
MVC ComplexityExplosion of flows
Courtesy: http://fluxxor.com/what-is-flux.html
MVC Complexity
Courtesy: http://fluxxor.com/what-is-flux.html
News
SummaryNews
One model powering 2 views
MVC Complexity
Courtesy: http://fluxxor.com/what-is-flux.html
News
SummaryNews
Friends
One model powering 2 views
Two models powering 1 view
MVC ComplexityExplosion of flows
Error in UI
MVC Complexity (cont.)Explosion of flows
Error in UI
MVC Complexity (cont.)Explosion of flows
Error in UI
MVC Complexity (cont.)Explosion of flows
Error in UI
Tracing LoopsDifficult:
● Tons of log entries○ Lots of things to look through○ Scrolling is laggy
● Cannot just look at snapshot for messy loops
MVC Simple Loops
Error in UI
Tracing (if set correctly) may tell you where loop is
MVC Looping the LoopExplosion of flows
Error in UI
Depending on where you look in the trace, you may think orange or bold loop
A loop resulting in another loop
MVC Simultaneous LoopsExplosion of flows
Error in UI
Tracing is difficult; seeing two traces
A loop resulting in multiple other loops concurrently
Flux
Courtesy: http://fluxxor.com/what-is-flux.html
Trigger ActionAction Done
Action DoneState Update
Structured and self-contained
Flux (cont.)
Courtesy: http://fluxxor.com/what-is-flux.html
Take ActionAction Done
Action DoneState Update
● Throttles one Action at a time● waitsFor()
● Synchronous tasks only● State and logic co-located
Flux (cont.)
Courtesy: http://fluxxor.com/what-is-flux.html
register register
With Flux
Courtesy: http://fluxxor.com/what-is-flux.html
Side-by-side
MVC Flux
Side-by-side● Structured growth (no path explosion):
○ Parallel stores lead to single top view
MVC Flux
Side-by-side● Structured growth (no path explosion):
○ Parallel stores lead to single top view○ Single-parent cascading views
MVC Flux
React
Side-by-side● Structured growth (no path explosion):
○ Parallel stores lead to single top view○ Single-parent cascading views
● Controllers-Models collapsed into Stores to co-locate logic & state
MVC Flux
React
Store
Store
With Flux
Error in UI
Only one trace at a time
● Dispatcher throttles Actions
A loop resulting in multiple other loops concurrently
With Flux
Error in UI
register
register
With Flux
Error in UI
register
register
Todo App
New Todo
Create
Todo #1
Todo #2Created Todo List
Action Creator Trigger<form>
<input id=’todo-text’ type=’text’ />
<button onClick=TodoActions.create($(‘#todo-text’).val())>Create</button>
</form>
Action CreatorTodoActions: { create: function(text) { // Take some action, e.g., call REST API AppDispatcher.dispatch({ actionType: TodoConstants.TODO_CREATE, // Basically ‘create’ text: text }); }, ….}
DispatcherAppDispatcher = require('flux').Dispatcher;
StoreAppDispatcher.register(function(action) { // action is passed in by Action Creatorvar event = action.event; switch(action.actionType) { case TodoConstants.TODO_CREATE: // Do whatever, e.g., update local store data or fetch fresh data from server TodoStore.emitChange(); break; …. }}
register
Store (cont.)var TodoStore = assign({}, EventEmitter.prototype, { // EventEmitter provides emit, on, removeListener, etc. methods addChangeListener: function(callback) { this.on(CHANGE_EVENT, callback); }, removeChangeListener: function(callback) { this.removeListener(CHANGE_EVENT, callback); }, emitChange: function() { this.emit(CHANGE_EVENT); }, ...}
register
Controller-View// This is where React is usedvar TodoApp = React.createClass({ componentDidMount: function() { TodoStore.addChangeListener(this._onChange); }, componentWillUnmount: function() { TodoStore.removeChangeListener(this._onChange); }, _onChange: function() { this.setState(TodoStore.getData()); }, ...}
register
Flux: More Pattern than Framework● Many implementations● Flux:
○ By Facebook
● Redux:○ Not pure Flux per se, but embraces its spirit○ Server-side rendering built-in○ Growing super-fast
● Alt:○ Pure Flux compliant○ Well-documented, great community○ Server-side rendering built-in
Flux Documentation Quirks● Uses native dispatcher, not the official Facebook dispatcher
○ Use official Facebook dispatcher
● Does not use Flux-Utils○ Use Flux-Utils to create Stores without code duplication
Rails with pure Flux: https://medium.com/@khor/back-to-front-rails-to-facebook-s-flux-ae815f81b16c
GraphQL: Data Retrieval
GraphQL
I speak GraphQL
API Endpoint
GraphQL (cont.)
API Endpoint
query { store(email: "[email protected]") { name, address }}
store(email: “[email protected]”) { name: ‘Hello Shop’, address: ‘1-3-1 Aoyama’}
GraphQL (cont.)
API Endpoint
query { store(email: "[email protected]") { categories { name, products { name, price, stock } } }}
store { categories: [ { name: ‘Sporting Goods’, products: [ { name: ‘Football’, price:, stock: 50 }, … }, ... ]}
From React example
GraphQL (cont.)
API Endpoint
query { store(email: "[email protected]") { categories { name, products { name, price, stock } } }}
store { categories: [ { name: ‘Sporting Goods’, products: [ { name: ‘Football’, price:, stock: 50 }, … }, ... ]}
Single endpoint
Nested data query
Client-specified query
Data in 1 round-trip
GraphQL (cont.)REST API:
● 3 endpoints:○ Endpoint for Store○ Endpoint for Category○ Endpoint for Product
● Server-controlled query○ Query for store returns email, name, address, etc. whether you want it or not
● Multiple round-trips vs. impure-REST/endpoint proliferation○ Get Store, get each Category, get each Product in each Category○ Lumping them together creates view-specific endpoints
GraphQL Enabled
https://github.com/rmosolgo/graphql-ruby
I speak GraphQL
API Endpoint
GraphQL: Schema # app/graph/types/query_type.rb
field :store do type StoreType # Shape of this type argument :email, !types.String, "Email of Store owner" ... # Retrieve data resolve -> (obj, args, ctx) do Store.find_by_email(args[:email]) # ActiveRecord stuff endend
query { store(email: "[email protected]") { name, address }}
GraphQL: Schema (cont.) # app/graph/types/store_type.rb
StoreType = GraphQL::ObjectType.define do name "Store" description "Store Data" … field :name, !types.String, "Store name" # From ActiveRecord field field :address, !types.String, "Store address" # From ActiveRecord field field :categories, !types[CategoryType], “Category list” # From ActiveRecord fieldend
query { store(email: "[email protected]") { name, address }}
GraphQL: Schema (cont.) # app/graph/types/store_type.rb
StoreType = GraphQL::ObjectType.define do name "Store" description "Store Data" … field :name, !types.String, "Store name" # From ActiveRecord field field :address, !types.String, "Store address" # From ActiveRecord field field :categories, !types[CategoryType], “Category list” # From ActiveRecord fieldend
query { store(email: "[email protected]") { categories { name, products { name, price, stock } } }}
GraphQL: Schema (cont.) # app/graph/types/category_type.rb
CategoryType = GraphQL::ObjectType.define do name "Category" description "Category Data" … field :name, !types.String, "Category name" # From ActiveRecord field field :products, !types[ProductType], “Product list” # From ActiveRecord field ...end
query { store(email: "[email protected]") { categories { name, products { name, price, stock } } }}
GraphQL: SummarySimplify:
● Efficient request for data that you need from server endpoint
Framework
● A single API endpoint to respond to query● Query language that enables client to specify data required, ala SQL● No over-fetch● Request all data in a single query
Relay: Component-Data Co-location
Relay: Declare Data
Relay: Declare Data
React: Recap (cont.)Fetch Data (AJAX)
React: Recap (cont.)
React: Recap (cont.)
Relay: GraphQL Fetch Relay/GraphQL
Relay: Why Data Declaration? Pass All Data
GraphQL/Relay Enabled
gem ‘graphql-ruby’
I speak GraphQL/Relay
API Endpoint
gem ‘graphql-relay-ruby’Relay Layer
‘react-relay’
Relay/GraphQL on Rails
Relay/GraphQL on Rails: https://medium.com/@khor/relay-facebook-on-rails-8b4af2057152
Relay: SummarySimplify
● Data fetching related stuff○ Show ‘Loading….’○ Data re-fetching○ Caching
■ Figuring out batching, reading/writing caching, fetching only missing pieces■ NOTE: Caching is NOT new but handling caching for hierarchical data is rather new
○ Managing errors, retry failed requests○ Optimistic updates○ Pagination
Framework
● Use GraphQL to fetch all required data declaratively● Handle all the above
How To Get Started Easily?● Make one piece of UI React● Make another piece React● Repeat until SPA
Which Should I UsePartly from: https://facebook.github.io/react/blog/2015/02/20/introducing-relay-and-graphql.html
Flux Relay/GraphQL
Multiple stores (one per domain) Single store (GraphQL server)
Explicit subscription Implied subscription based on data required
Actions (possibly with AJAX) Mutations (query with changes)
REST API pros, and cons Efficient data handling (batching, caching, no over-fetching, etc.)
More customized coding Generic framework for data access, updates, etc.
Prefer imperative debugging Love magic, abstractions, and puzzle debugging
Other Stuff● React
○ Must all user-interaction go to top? Must top do all data manipulation?
● GraphQL○ Can I just use GraphQL? Do I need Relay?
● Relay○ How to modify Model without AJAX?○ There is no gem?
Thank You!
Primary ResourcesThinking in React: https://facebook.github.io/react/docs/thinking-in-react.html
Flux Best Practices: https://facebook.github.io/flux/docs/flux-utils.html
Nested Relay Components: https://facebook.github.io/react/blog/2015/03/19/building-the-facebook-news-feed-with-relay.html
Practical ResourcesRails with pure Flux: https://medium.com/@khor/back-to-front-rails-to-facebook-s-flux-ae815f81b16c
Relay/GraphQL on Rails: https://medium.com/@khor/relay-facebook-on-rails-8b4af2057152
Relay/GraphQL Rails Starter Kit: https://github.com/nethsix/relay-on-rails
ReferencesFlux Comparisons:
● https://medium.com/social-tables-tech/we-compared-13-top-flux-implementations-you-won-t-believe-who-came-out-on-top-1063db32fe73
● http://jamesknelson.com/which-flux-implementation-should-i-use-with-react/
Introduction to GraphQL: http://facebook.github.io/react/blog/2015/02/20/introducing-relay-and-graphql.html
Thinking In GraphQL: https://facebook.github.io/relay/docs/thinking-in-graphql.html
Thinking In Relay: https://facebook.github.io/relay/docs/thinking-in-relay.html